south korean rap sensation psy into the spot light. the most-watched youtube video ever. tonight, his lyrics from years ago and anti-american words are causing anger here at home, just as he prepares to perform for the president. here's muhammad lila. >> reporter: call it controversy, "gangnam style." long before it sparked a dance craze, he performed at a politically charged concert in 2004 with anti-american sentiment running high after a korean missionary was killed in iraq. he sang these lyrics. kill those bleeping yankees who have been keeping them hostage. kill their daughters, mothers, daughters in law and fathers. >> if you were thinking of horrible things that could get pop stars in trouble, you would have a hard time coming up with worse things than this. >> reporter: many fans are reacting with fury, saying spy should not be able to headline the christmas in washington concert on sunday. the president scheduled to attend. this is not the first time an artist has courted a political controversy. but this is different. spy is